1. Field
The present disclosure relates to a metal-doped oxide, a method of preparing the same, and a solid oxide electrolyte using the metal-doped oxide.
2. Description of the Related Art
Fuel cells are an example of an alternative energy source, and can be classified as a polymer electrolyte membrane fuel cell (“PEMFC”), a phosphoric acid fuel cell (“PAFC”), a molten carbonate fuel cell (“MCFC”), or a solid oxide fuel cell (“SOFC”) according to the type of electrolyte.
SOFCs include an ionically conductive solid oxide electrolyte. SOFCs can provide high efficiency, excellent durability, and relatively low manufacturing cost, and can use a variety of fuels.
An output voltage of a SOFC may be calculated using equation I below.Equation IV=Voc−i(Relectrolyte+Rcathode+Ranode)−ηcathode−ηanode 
In equation I, V is the output voltage, Voc is the open circuit voltage, i is current, and Relectrolyte, Rcathode, and Ranode are respectively the resistance of an electrolyte, a cathode, and an anode, and ηcathode and ηanode are the concentration polarization of the cathode and anode, respectively. In equation I, i(Releotrolyte+Rcathode+Ranode) is the resistance polarization.
The actual output voltage of a SOFC is lower than its theoretical output voltage because of the resistance of the solid oxide electrolyte, the negative electrode, and the positive electrode as shown in equation I above. The solid oxide electrolyte inhibits air and fuel from mixing between the negative and positive electrodes, supports the negative and positive electrodes, and allows oxygen ions to transport (i.e., diffuse) from the positive electrode to the negative electrode.
Therefore, there remains a need to reduce the resistance of the electrolyte in order to increase the output voltage of the SOFC. In other words, there remains a need for a solid oxide electrolyte having higher ionic conductivity.